Apparatus for changing the pitch angle of reversible-blade screw propellers



2- Sheets-Sheet l M. D. THOMPSON APPARATUS FOR CHANGING THE PITCH ANGLEOF REVERSIBLE BLADE SCREW PROPELLERS Filed Nov.

Feb. 21, 1933.

INV E NTO R Milton D.Thomjzson.

WTTuRmrY.

. Feb. 21, 1933. J M; D. THOMPSON 1,898,697

APPARATUS FOR CHANGING THE PITCH ANGLE OF REVERSIBLE BLADE SCREWPROPELLERS Filed Nov. '9. 1931 Z'Shefls-Sheet 2 IHVEHTOR.

JIilton D. Thompson.

Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE MILTON D. THOMPSON,OF FAIBHAVEN, MASSACHUSETTS APPARATUS FOR CHANGING THE PITCH ANGLE OFREVERSIBLE-BLADE SCREW PROPELLEBS Application filed November 9, 1931.

I The invention hereinafter to be described relates, in general terms,to propelling machinery for Various kinds of water craft,

and deals more particularly with certain im-- solid propeller, or one inwhich the blades are cast integral with the propeller hub. In most casesthis is quite satisfactory on account of the fact that the steam engineis not only reversible with respect to the direction of rotation of itsshaft but is also susceptible of being driven at rotation.

The modern trend, however, is away from steam and toward the use of gasor internal greatly varying speeds of combustion engines and these beinggenerally irreversible giowe'r agents and more economically and eciently operated at a constant or uniform speedof rotation it becomesnecessary to provide certain apparatus by means of which the drivingeffort of the propeller may be made variable so as to move the vessel atdifferent speeds, and also to supply means to apply this driving effortin opposite directions in order that the craft may be moved either in aforward or backward direction.

Reversing and speed reducing gear sets are sometimes employed toaccomplish the above objects, although in certain respects they lacktheessential requirements which are embodied in other blade-reversingmechpower, and a solid propeller in these instances becomes a drag, andnecessarily greatly reduces the speed of the craft when operating whollyby wind power.

In the present invention I employ a differential gear mechanism which ispower driven from the main shaft" of the engine and which Serial No.578,868.

can be made to actuate a feed screw for the purpose of changing thepitch angle of the blades of the propeller while the engine is operatingat fullor normal speed.

By applying a brake to either one, singly, of two geared brake drums thefeed screw is set in motion and moved longitudinally of the shaft andthe blades turned on their axes in a direction determined by which ofthe two drums is restricted in its rotary movement..

Upon releasing the brake the blades remain 1 in a positively secured andpredetermined angular position.

An automatic feed stop arrangement prevents further axial rotation ofthe blades when either extreme of pitch angle, forwardly or backwardly,is reached, and an indicator shows the particular pitch angle or lead atwhichthe blades are disposed at the time.

Facilities are also provided for correcting the pitch of each individualblade, and this is a feature which is of superior advantage in themanner of attaining and preserving correct balance of the propellerwheel.

The character of the invention may best be understood by reference tothe description found in the following specification when taken inconnection with the accompanying drawings in which is disclosedanembodiment thereof which, at the present time, I consider preferableto other possible forms in which the invention might be carried out.

In the drawings- Fig. 1 is a sectional plan view of my apparatus;

Fig. 2 is an end view of the propeller hub, the cap being removed toshow the link block;

Fig. 3 is a section on line 3-3, Fig. 1.

Fig. 4 is a composite view, in perspective, showing the foot of theblade and the split collar which secures it to the propeller hub;

Fig. 5 is a diagrammatical view showing the method of connecting thelink block to the blade;

Fig. 6 shows, on an enlarged scale, the eccentric pin which is employedto locate the link in various positions on the link block;

Fig. 7 is an end view of a propeller blade shown in full lines to repr.esent neutral or feathering position, and in dotted lines for aheadand astern positions, respective- 1 YFig. 8 shows an alternate method ofsecuring the two parts of the housing together;

Fig. 9 is afull plan view of the apparatus, the propeller not beingshown;

F ig. 10 is a side view of one of the brake bands;

Fig. 11 is a detail view of the automatic stop mechanism;

Fig. 12 shows the cammed face of the brake band ear;

Fig. 13 is a perspective view of the slotted sleeve-actuating lever forthe automatic stop mechanism;

Fig. 14 illustrates the position of the indicating elements when theblades have moved to one extreme outward position of pitch angle;

lgig. 15 is a section on line 15-15, Fig. '9, an

Fig. 16 is a perspective view of the indicator end of the feed screw.

Similar reference characters are employed to identify like parts in allthe difierent views of the drawings.

Referring to the drawings, and particularly to Fig. 1, it will beobserved that the principal working parts of the mechanism are enclosedin a longitudinally and centrally split housing consisting of twosimilar structures, 1 and 2, which, when the apparatus is in operationis partially filled with a proper lubricant.

On each end of the housing proper are extended split hubs 1a and 2a and1b and 2?), respectively, and through the hubs is a bore 3 a portion ofwhich, at 3a, is made square 1n cross section.

On the extreme inner ends of the hubs 1a and 2a are semi-circularflanges 4a and 4b which are secured to the solid circular flangecoupling 5 fixed on the main engine shaft 6.

Operating in the bore 3 is a feed screw 7, on the outer end of which isfixed the feed rod 8 extending through the bore 9 in the propeller shaft10 to the link block 11, which latter is slidably mounted in the hub 12of the propeller.

Disposed between the bosses 13, 13, is a bevel gear 14 which is screwthreaded in its bore and operates on the feed screw 7. Meshing with anddisposed on opposite sides of the gear 14 are two smaller bevel gears15, 15, which are fixed, respectively, on shafts 16, 16 which arejournalled in bearings 17, 17.

These shafts diverge, relatively, toward the forward end of the housingand on one end of each is fixed a gear 18, these two gears (18) meshingwith and located on opposite sides of the external gear 19 which issecured to the brake drum 20. On the inner ends, respectively, of theshafts 16 are gears 21, these meshing with the internal gear 22 which issecured to the brake drum 23.

Operating, respectively, on the brake drums 20 and 23 are brake bands24, 24, a side View of one of which is shown in Fig. 10. On the face ofthe band projects an ear 25 fixed on a supporting standard 26, and onthe open ends of the band are other ears 27 on one of which is a cammedface (see Fig. 12) adapted to engage the reversely camme surface of thebrake arm 28. A bolt 29 passes through both the ears 27 and the cammedbrake arm operates between the head of the bolt and the cammed car so asto effect, when the arm is swung in one direction, a closing together ofthe brake bandends and tightly bind the band to the drum. An upstandinglever 30 is employed to actuate the brake arm.

To secure the two halves of the housing together I employ rings 31 and32 having screw threaded engagement with correspondingly threadedportions 33 and 34, respectively, on the ends of the housing membersl InFig. 8 is shown a modification in the method of securing the two membersof the housing together, bolts 35 being employed in this instance.

The propeller blade 36 is axially rotatable in a split collar 37 whichsurrounds the shank or reduced portion of the foot of the blade, 38, andis screw threaded on its periphery into the opening 39 in the hub 12. Aset screw 40 prevent rotation of the collar and a cap 41, threaded tothe end of the hub, at 42, seats on the shoulder 43 and prevents backingout of the screws 40.

It will be observed that the link block 11 is provided with a guide rod44 which passes through the end of the cap. This prevents any pumpingaction which might occur was the hole not carried completely through thecap.

To hold the link block 11, which preferably is made triangular in crosssection, against rotation in the hub 12 I provide indents 45 in whichthe apices of the block seat and in which they may longitudinally slide.

On the inner face of each blade, at the foot end, is a crank pin 46 andon each face of the link block is an eccentrically mounted pin 47Operable over and connecting with both of these pins is a link 48.

Referring to Figs. 5 and 7 it will be seen how longitudinal movement ofthe link block rotates the propeller bade. The small circle a:represents the axis of the blade and around this central point swingsthe pin 46 on the blade. When the pin 46 is positioned on the radialline a the blade is set at extreme working pitch ahead, and when onradial line b it is on extreme working 'pitclrastern.

When it is desired to feather the bladesfore and aft-the pin 46 is movedto radial.

line a, in which position the link rests on the stop pin 49. Theeccentric pin 47 moves longitudinally, backwardly and forwardly with thelink block, in exactly the same manner as would the wrist-pin in acrosshead of a steam engine; and to complete the analogy, the link 48serves in the same capacity as does the connecting-rod of the engine.

Due to possible inaccuracies in locating the pins or to slightdissimilarities in the pitch of the blades when molding or finishing Ihave found that it is 'quite essential that means be provided to bringall the blades to a uniform pitch angle after assembling them on thepropeller hub.

To accomplish this object I make the pin 47 eccentric (see Fig. 6) andby slightly turning it in its position in the block it has the effect ofre-positioning the linkas shown in dot and dash lineswith a consequentchange in the angularity of the blade in its position on the hub of thepropeller.

The actuation of the brake arms .28 to effect difi'erent changes inpitch angles of the" blades is a manual operation performed by theengineer or other attendant in charge and he is supposed to release thebrake drums and stop the feeding of the feed screw when the desiredpitch angle has been reachedas visually disclosed by the indicator. Butin careless operating he might neglect to throw off the brake at theproper time with the result that damage might be done to the parts. Forthis reason I consider it quite essential that the automatic stop-feedmechanism be incorporated in the structure of the apparatus.

In Fig. 14 the feed stop arm 50 is shown contacting with the collar 51at a point indicated by the pointer as being the extreme pitch of theblade when working astern.

Regardless of whether the engineer retains his grip on the brake leverafter reaching the extreme working pitch point, or not, the

automatic safety knock-off will act to release the brake at the propertime.

In operating the ahead brake drum the automatic knock-ofi' or feed stoparm .50 will act on the collar only when the pin 16 has reached aposition coincident with the radial line a. (Fig. 5) or at a point atwhich the blades. are feathering; but unless the vessel is sup lied witha large surplus of power it would be extremely difiicult to operate thepropeller with the blades standing fore and aft as their flat faceswould be presented tothe water. In cases of emergency the collar 52would act, however.

When the propeller shaft is not rotating and it is desired to change thepitch of the blades-as for instance, in a sail equipped and the chain ofgears set in motion to move the screw 7 in either direction.

The automatic sto parts are shown in neutral position in igs. 1 and 9.In Fig. 11 the screw 7 has been moved toward the propeller, the asternbrake band having been tightened, causing the slotted lever 53 to swingand move the grooved sleeve 54 forwardly and the feed stop arm 50 intothe position shown in Fig. 14.

By reference to Fig. 15 it will be noted that there are two of theslotted levers 53, one operating in a depression 55 in the housing part154- and another in a like depression in the housing part 2a. Thisprevents cramping of the sleeve as -it moves over the housing hubs.

The numerals O, 10, 20 etc. disposed in an are on the indicator boards Bmay represent either pitch angles or leads in inches of the screw shapedblade; they are of considerable advantage'to the engineer in correctlymanipulating the friction bands in order to bring the blades to somepredetermined position.

The coupling 56 joins the housing parts,v

1 and 2, to the propeller shaft 10, keys 5'? and set screws 58 beingemployed to securethe parts together.

It will be observed by reference to Fig. 3 that the screw member 7 ismade square adjacent ,the portion 3a of the bore. This is to preventturning of the screw when the gear Let us assume, first, that the enginero- 1 tates right hand, that is, according to the direction indicated bythe arrow on the shaft coupling, shown in Fig. 9 also let it beunderstood that in this instance the astern brake band has beentightened, as shown in dotted lines Fig. 9. Now, the engine beingoperated, all parts of the apparatus supported on the main shaft line,except the two brake bands, the brake drum 23 and the gear 22, arerevolving.

But, while the gears 21 rotate bodily with and around the axis of thehousing parts, they also rotate on their own axes, due to theirengagement with the gear 22 which for the time being is stationary as itis fixed on the drum 23, which is being held rigid by the band.

The shafts 16 thus rotate at this time in their respective bearings andon their own axes, and the gears 15 being fixed on these.

shafts and also in engagement with the gear 14, impart v rotary movementto the latter which acts as would an ordinary nut turning on the feedscrew 7, the latter rotating with but not in the housing parts.

There is, therefore, a longitudinal movement given the screw 7 which iscommunicated by means of the feed rod 8 to the link block 11, andthrough the instrumentality of the links 48 interconnecting the pins 46and 4:7 in the manner hereinbefore set forth, a rotary movement of theblades is finally accomplished, turning them in the present instance sothat they lie in coincidence with the line b-Z), Fig. 7-which representsthe blade when in left hand pitch, the line w-a, Fig. 7 corresponding toright hand pitch angle. I

The counter-rod 57 supporting the collars 51, 51a and 52 may besupported in suitable hea rings (not shown), the yoked ends of the brakearms straddling the rod and engaging the collars when the brakes arebeing operated.

The embodiment herein described is, of course, primarily illustrativeand my invention is, obviously, capable of interpretation in a widevariety of structures.

What I claim is:

1. In apparatus of the class described adapted for use on shafts forscrew propel- .lers having detachable blades, comprising a housingsecured to and revoluble with said propeller shaft, a feed screw in saidhousing extending through a bore in said propeller shaft to saidpropeller, a gear having a threaded bore mounted on said feed screw, adrum rcvoluble on said housing, a gear fixed to said drum, a shaft, theaxis of which is inclined from the axis of said propeller shaft,journalled in said housing, two gears fixedly mounted on said inclinedshaft adapted to engage, respectively, the two first mentioned gears,and means whereby, when said propeller shaft and said housing arerevolving, said drum may be held against. rotation, causing adifferential gear action to be had between the respective gears, thefirst gear mentioned rotating on said feed screw and moving itlongitudinally in one direction in the bore of said propeller shaft.

2. In apparatus of the class described adapted for use in connectionwith the operation of changing the pitch angle of the blades of areversible screw propeller mounted on a hollow shaft, comprising ahousing mounted on said shaft and having a central bore therein, a feedscrew operable in said central bore,a gear, having a screw-threadedbore, mounted on said feed screw and held against longitudinal movementin said housing, a differential gear set in said housing operable torotate said feed screw gear on said feed screw in two directions whilesaid housing is revolving in but one direction, a feed-rod connectingwith said feed screw and extending through said hollow shaft to theinteriorof the hub of said propeller, a link block fixed on the outerend of said feed rod and having faces the number of which correspond tothe number of blades in said propeller, an eccentrically mounted pin oneach face of said link block, a crankpin on the inner end of each ofsaid blades, and a link interconnecting the two said pins, saideccentrically mounted. pin providing means to re-locate said link on andlongitudinally of said link block whereby adjustments may be made tobring all of said blades into uniformity with respect to their pitchangles.

3. In apparatus of the class described adapted for use on hollow shaftsfor screw propellers having reversible blades comprising a centrally andlongitudinally split housing, means to secure the two halves of 'saidhousing together, a central bore through said housing, a feed screwoperable in said bore and having a portion extending to and into the hubof said propeller, a gear having a threaded bore mounted on said feedscrew, two brake drums revolubly mounted, respectively, on the two endsof said housing, a gear fixed on'each of said brake drums, interiorly ofsaid housing, two shafts journalled in said housing on opposite sides,respectively, of said feed screw, their axes being inclined from theaxis of said screw, three gears fixedly mounted on each of said inclinedshafts, one on each end and the third intermediate the length of theshaft, one end gear adapted to engage, externally, one of the brake drumgears and the other end gear meshing, internally, with the gear on theoppositely disposed brake drum, with the intermediate gear on each ofsaid inclined shafts meshing with the said feed screw gear, a brake bandon each of said brake drums, means to tighten, singly, either of saidbrake bands and hold the drum on which it is mounted against rotationwhile said housing is revolving, a link block on the end of sald feedscrew extension, and means to connect said link block with each of theblades of said prope ller whereby they may be rotated, axially, in theirmountings on the hub of saidpropeller.

4. In apparatus of the class described adapted for use on hollow shaftsfor screw propellers having reversible blades comprising a housingmounted on said shaft, a differential gear set in said housing, a feedscrew axially mounted in said housing and adaptable of longitudinalmovement, only, therein, a drum revoluble on each end of said housing, abrake band on each of said drums, a brake arm on each of said bandsadapted when swung in one direction to cause said band to becometightened on and hold said drum against rotation while said housing isrevolv ing, the stopping of rotation of one drum acting, in associationwith said-gear set, to

move said feed screw in one direction, and by the stoppage of the otherdrum to reverse the movement of said feed screw longitudinally,

and a pivotally mounted feed-stop arm one end of which is actuated bysaid feed screw and the other end operable to automatically release thebrake band on. the operating drum whereby the longitudinal movement ofsaid screw ceases.

5. In apparatus for changing the pitch an- I gle of reversible bladescrew propellers comprising a hollow shaft on one end of which apropeller is mounted, a housing secured to the opposite end of saidhollow shaft, a feed screw trarersing said housing and said hollowshaft, interiorly of both, a feed gear, having a screw-threaded bore,operable on said feed screw, means to hold said feed screw againstlongitudinal movement in said housing, a brake drum revoluble on eachend of said housing, braking means applicable to hold said drums,singly, against rotation on said housing, a dilferential gear setinterconnecting and associated with both of said drums and said feedgear and arranged within said housing in such a manner that, when saidhousing is revolving, stoppage of rotation of said drums alternatelywill rotate said feed gear, respectively, in two directions, with aconsequent and corresponding longitudinal movement of said feed screw,and means cooperating with said feed screw to release the brake oneither of said drums aft er said feed screw has moved longitudinally insaid housing a predetermined distance in either direction.

In testimony whereof I aflix my si ature.

MILTON D. THOMP ON.

